/*	$OpenBSD: rf_pqdegdags.c,v 1.4 2000/01/07 14:50:22 peter Exp $	*/
/*	$NetBSD: rf_pqdegdags.c,v 1.5 1999/08/15 02:36:40 oster Exp $	*/

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Daniel Stodolsky
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/*
 * rf_pqdegdags.c
 * Degraded mode dags for double fault cases.
 */


#include "rf_archs.h"

#if	(RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagdegrd.h"
#include "rf_dagdegwr.h"
#include "rf_dagfuncs.h"
#include "rf_dagutils.h"
#include "rf_etimer.h"
#include "rf_acctrace.h"
#include "rf_general.h"
#include "rf_pqdegdags.h"
#include "rf_pq.h"

void rf_applyPDA(RF_Raid_t *, RF_PhysDiskAddr_t *, RF_PhysDiskAddr_t *,
	RF_PhysDiskAddr_t *, void *);

/*
 * Two data drives have failed, and we are doing a read that covers one of them.
 * We may also be reading some of the surviving drives.
 */


/*****************************************************************************
 *
 * Creates a DAG to perform a degraded-mode read of data within one stripe.
 * This DAG is as follows:
 *
 *			                Hdr
 *			                 |
 *			               Block
 *			 /         /           \         \     \   \
 *			Rud  ...  Rud         Rrd  ...  Rrd    Rp  Rq
 *			| \       | \         | \       | \    | \ | \
 *
 *			           |                 |
 *			        Unblock              X
 *			            \               /
 *			             ------ T ------
 *
 * Each R node is a successor of the L node.
 * One successor arc from each R node goes to U, and the other to X.
 * There is one Rud for each chunk of surviving user data requested by the
 * user, and one Rrd for each chunk of surviving user data _not_ being read
 * by the user.
 * R = read, ud = user data, rd = recovery (surviving) data, p = P data,
 * q = Qdata, X = pq recovery node, T = terminate
 *
 * The block & unblock nodes are leftovers from a previous version. They
 * do nothing, but I haven't deleted them because it would be a tremendous
 * effort to put them back in.
 *
 * Note:  The target buffer for the XOR node is set to the actual user buffer
 * where the failed data is supposed to end up. This buffer is zero'd by the
 * code here. Thus, if you create a degraded read dag, use it, and then
 * re-use. You have to be sure to zero the target buffer prior to the re-use.
 *
 * Every buffer read is passed to the pq recovery node, whose job it is to
 * sort out what's needed and what's not.
 *****************************************************************************/

/* Init a disk node with 2 successors and one predecessor. */
#define	INIT_DISK_NODE(node,name)					\
do {									\
	rf_InitNode(node, rf_wait, RF_FALSE, rf_DiskReadFunc,		\
	    rf_DiskReadUndoFunc, rf_GenericWakeupFunc, 2, 1, 4, 0,	\
	    dag_h, name, allocList);					\
	(node)->succedents[0] = unblockNode;				\
	(node)->succedents[1] = recoveryNode;				\
	(node)->antecedents[0] = blockNode;				\
	(node)->antType[0] = rf_control;				\
} while (0)

#define	DISK_NODE_PARAMS(_node_,_p_)					\
do {									\
	(_node_).params[0].p = _p_ ;					\
	(_node_).params[1].p = (_p_)->bufPtr;				\
	(_node_).params[2].v = parityStripeID;				\
	(_node_).params[3].v = RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY,	\
	    0, 0, which_ru);						\
} while (0)

#define	DISK_NODE_PDA(node)	((node)->params[0].p)

RF_CREATE_DAG_FUNC_DECL(rf_PQ_DoubleDegRead)
{
	rf_DoubleDegRead(raidPtr, asmap, dag_h, bp, flags, allocList,
	    "Rq", "PQ Recovery", rf_PQDoubleRecoveryFunc);
}

void
rf_applyPDA(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *pda,
    RF_PhysDiskAddr_t *ppda, RF_PhysDiskAddr_t *qpda, void *bp)
{
	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
	RF_RaidAddr_t s0off = rf_StripeUnitOffset(layoutPtr, ppda->startSector);
	RF_SectorCount_t s0len = ppda->numSector, len;
	RF_SectorNum_t suoffset;
	unsigned coeff;
	char *pbuf = ppda->bufPtr;
	char *qbuf = qpda->bufPtr;
	char *buf;
	int delta;

	suoffset = rf_StripeUnitOffset(layoutPtr, pda->startSector);
	len = pda->numSector;
	/* See if pda intersects a recovery pda. */
	if ((suoffset < s0off + s0len) && (suoffset + len > s0off)) {
		buf = pda->bufPtr;
		coeff = rf_RaidAddressToStripeUnitID(&(raidPtr->Layout),
		    pda->raidAddress);
		coeff = (coeff % raidPtr->Layout.numDataCol);

		if (suoffset < s0off) {
			delta = s0off - suoffset;
			buf += rf_RaidAddressToStripeUnitID(&(raidPtr->Layout),
			    delta);
			suoffset = s0off;
			len -= delta;
		}
		if (suoffset > s0off) {
			delta = suoffset - s0off;
			pbuf += rf_RaidAddressToStripeUnitID(&(raidPtr->Layout),
			    delta);
			qbuf += rf_RaidAddressToStripeUnitID(&(raidPtr->Layout),
			    delta);
		}
		if ((suoffset + len) > (s0len + s0off))
			len = s0len + s0off - suoffset;

		/* Src, dest, len. */
		rf_bxor(buf, pbuf, rf_RaidAddressToByte(raidPtr, len), bp);

		/* Dest, src, len, coeff. */
		rf_IncQ((unsigned long *) qbuf, (unsigned long *) buf,
		    rf_RaidAddressToByte(raidPtr, len), coeff);
	}
}


/*
 * Recover data in the case of a double failure. There can be two
 * result buffers, one for each chunk of data trying to be recovered.
 * The params are pda's that have not been range restricted or otherwise
 * politely massaged - this should be done here. The last params are the
 * pdas of P and Q, followed by the raidPtr. The list can look like
 *
 *   pda, pda, ..., p pda, q pda, raidptr, asm
 *
 * or
 *
 *   pda, pda, ..., p_1 pda, p_2 pda, q_1 pda, q_2 pda, raidptr, asm
 *
 * depending on whether two chunks of recovery data were required.
 *
 * The second condition only arises if there are two failed buffers
 * whose lengths do not add up a stripe unit.
 */

int
rf_PQDoubleRecoveryFunc(RF_DagNode_t *node)
{
	int np = node->numParams;
	RF_AccessStripeMap_t *asmap =
	    (RF_AccessStripeMap_t *) node->params[np - 1].p;
	RF_Raid_t *raidPtr = (RF_Raid_t *) node->params[np - 2].p;
	RF_RaidLayout_t *layoutPtr = (RF_RaidLayout_t *) & (raidPtr->Layout);
	int d, i;
	unsigned coeff;
	RF_RaidAddr_t sosAddr, suoffset;
	RF_SectorCount_t len, secPerSU = layoutPtr->sectorsPerStripeUnit;
	int two = 0;
	RF_PhysDiskAddr_t *ppda, *ppda2, *qpda, *qpda2, *pda, npda;
	char *buf;
	int numDataCol = layoutPtr->numDataCol;
	RF_Etimer_t timer;
	RF_AccTraceEntry_t *tracerec = node->dagHdr->tracerec;

	RF_ETIMER_START(timer);

	if (asmap->failedPDAs[1] &&
	    (asmap->failedPDAs[1]->numSector +
	     asmap->failedPDAs[0]->numSector < secPerSU)) {
		RF_ASSERT(0);
		ppda = node->params[np - 6].p;
		ppda2 = node->params[np - 5].p;
		qpda = node->params[np - 4].p;
		qpda2 = node->params[np - 3].p;
		d = (np - 6);
		two = 1;
	} else {
		ppda = node->params[np - 4].p;
		qpda = node->params[np - 3].p;
		d = (np - 4);
	}

	for (i = 0; i < d; i++) {
		pda = node->params[i].p;
		buf = pda->bufPtr;
		suoffset = rf_StripeUnitOffset(layoutPtr, pda->startSector);
		len = pda->numSector;
		coeff = rf_RaidAddressToStripeUnitID(layoutPtr,
		    pda->raidAddress);
		/* Compute the data unit offset within the column. */
		coeff = (coeff % raidPtr->Layout.numDataCol);
		/* See if pda intersects a recovery pda. */
		rf_applyPDA(raidPtr, pda, ppda, qpda, node->dagHdr->bp);
		if (two)
			rf_applyPDA(raidPtr, pda, ppda, qpda, node->dagHdr->bp);
	}

	/*
	 * Ok, we got the parity back to the point where we can recover. We
	 * now need to determine the coeff of the columns that need to be
	 * recovered. We can also only need to recover a single stripe unit.
	 */

	if (asmap->failedPDAs[1] == NULL) {	/*
						 * Only a single stripe unit
						 * to recover.
						 */
		pda = asmap->failedPDAs[0];
		sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr,
		    asmap->raidAddress);
		/* Need to determine the column of the other failed disk. */
		coeff = rf_RaidAddressToStripeUnitID(layoutPtr,
		    pda->raidAddress);
		/* Compute the data unit offset within the column. */
		coeff = (coeff % raidPtr->Layout.numDataCol);
		for (i = 0; i < numDataCol; i++) {
			npda.raidAddress = sosAddr + (i * secPerSU);
			(raidPtr->Layout.map->MapSector) (raidPtr,
			    npda.raidAddress, &(npda.row), &(npda.col),
			    &(npda.startSector), 0);
			/* Skip over dead disks. */
			if (RF_DEAD_DISK(raidPtr->Disks[npda.row][npda.col]
			    .status))
				if (i != coeff)
					break;
		}
		RF_ASSERT(i < numDataCol);
		RF_ASSERT(two == 0);
		/*
		 * Recover the data. Since we need only to recover one
		 * column, we overwrite the parity with the other one.
		 */
		if (coeff < i)	/* Recovering 'a'. */
			rf_PQ_recover((unsigned long *) ppda->bufPtr,
			    (unsigned long *) qpda->bufPtr,
			    (unsigned long *) pda->bufPtr,
			    (unsigned long *) ppda->bufPtr,
			    rf_RaidAddressToByte(raidPtr, pda->numSector),
			    coeff, i);
		else		/* Recovering 'b'. */
			rf_PQ_recover((unsigned long *) ppda->bufPtr,
			    (unsigned long *) qpda->bufPtr,
			    (unsigned long *) ppda->bufPtr,
			    (unsigned long *) pda->bufPtr,
			    rf_RaidAddressToByte(raidPtr, pda->numSector),
			    i, coeff);
	} else
		RF_PANIC();

	RF_ETIMER_STOP(timer);
	RF_ETIMER_EVAL(timer);
	if (tracerec)
		tracerec->q_us += RF_ETIMER_VAL_US(timer);
	rf_GenericWakeupFunc(node, 0);
	return (0);
}

int
rf_PQWriteDoubleRecoveryFunc(RF_DagNode_t *node)
{
	/*
	 * The situation:
	 *
	 * We are doing a write that hits only one failed data unit. The other
	 * failed data unit is not being overwritten, so we need to generate
	 * it.
	 *
	 * For the moment, we assume all the nonfailed data being written is in
	 * the shadow of the failed data unit. (i.e., either a single data
	 * unit write or the entire failed stripe unit is being overwritten.)
	 *
	 * Recovery strategy: apply the recovery data to the parity and Q.
	 * Use P & Q to recover the second failed data unit in P. Zero fill
	 * Q, then apply the recovered data to P. Then apply the data being
	 * written to the failed drive. Then walk through the surviving drives,
	 * applying new data when it exists, othewise the recovery data.
	 * Quite a mess.
	 *
	 *
	 * The params:
	 *
	 *   read pda0, read pda1, ..., read pda (numDataCol-3),
	 *   write pda0, ..., write pda (numStripeUnitAccess - numDataFailed),
	 *   failed pda, raidPtr, asmap
	 */

	int np = node->numParams;
	RF_AccessStripeMap_t *asmap = (RF_AccessStripeMap_t *)
	    node->params[np - 1].p;
	RF_Raid_t *raidPtr = (RF_Raid_t *) node->params[np - 2].p;
	RF_RaidLayout_t *layoutPtr = (RF_RaidLayout_t *) & (raidPtr->Layout);
	int i;
	RF_RaidAddr_t sosAddr;
	unsigned coeff;
	RF_StripeCount_t secPerSU = layoutPtr->sectorsPerStripeUnit;
	RF_PhysDiskAddr_t *ppda, *qpda, *pda, npda;
	int numDataCol = layoutPtr->numDataCol;
	RF_Etimer_t timer;
	RF_AccTraceEntry_t *tracerec = node->dagHdr->tracerec;

	RF_ASSERT(node->numResults == 2);
	RF_ASSERT(asmap->failedPDAs[1] == NULL);
	RF_ETIMER_START(timer);
	ppda = node->results[0];
	qpda = node->results[1];
	/* apply the recovery data */
	for (i = 0; i < numDataCol - 2; i++)
		rf_applyPDA(raidPtr, node->params[i].p, ppda, qpda,
		    node->dagHdr->bp);

	/* Determine the other failed data unit. */
	pda = asmap->failedPDAs[0];
	sosAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr,
	    asmap->raidAddress);
	/* Need to determine the column of the other failed disk. */
	coeff = rf_RaidAddressToStripeUnitID(layoutPtr, pda->raidAddress);
	/* Compute the data unit offset within the column. */
	coeff = (coeff % raidPtr->Layout.numDataCol);
	for (i = 0; i < numDataCol; i++) {
		npda.raidAddress = sosAddr + (i * secPerSU);
		(raidPtr->Layout.map->MapSector) (raidPtr, npda.raidAddress,
		    &(npda.row), &(npda.col), &(npda.startSector), 0);
		/* Skip over dead disks. */
		if (RF_DEAD_DISK(raidPtr->Disks[npda.row][npda.col].status))
			if (i != coeff)
				break;
	}
	RF_ASSERT(i < numDataCol);
	/*
	 * Recover the data. The column we want to recover, we write over the
	 * parity. The column we don't care about, we dump in q.
	 */
	if (coeff < i)		/* Recovering 'a'. */
		rf_PQ_recover((unsigned long *) ppda->bufPtr,
		    (unsigned long *) qpda->bufPtr,
		    (unsigned long *) ppda->bufPtr,
		    (unsigned long *) qpda->bufPtr,
		    rf_RaidAddressToByte(raidPtr, pda->numSector), coeff, i);
	else			/* Recovering 'b'. */
		rf_PQ_recover((unsigned long *) ppda->bufPtr,
		    (unsigned long *) qpda->bufPtr,
		    (unsigned long *) qpda->bufPtr,
		    (unsigned long *) ppda->bufPtr,
		    rf_RaidAddressToByte(raidPtr, pda->numSector), i, coeff);

	/* OK. The valid data is in P. Zero fill Q, then inc it into it. */
	bzero(qpda->bufPtr, rf_RaidAddressToByte(raidPtr, qpda->numSector));
	rf_IncQ((unsigned long *) qpda->bufPtr, (unsigned long *) ppda->bufPtr,
	    rf_RaidAddressToByte(raidPtr, qpda->numSector), i);

	/* Now apply all the write data to the buffer. */
	/*
	 * Single stripe unit write case: The failed data is the only thing
	 * we are writing.
	 */
	RF_ASSERT(asmap->numStripeUnitsAccessed == 1);
	/* Dest, src, len, coeff. */
	rf_IncQ((unsigned long *) qpda->bufPtr,
	    (unsigned long *) asmap->failedPDAs[0]->bufPtr,
	    rf_RaidAddressToByte(raidPtr, qpda->numSector), coeff);
	rf_bxor(asmap->failedPDAs[0]->bufPtr, ppda->bufPtr,
	    rf_RaidAddressToByte(raidPtr, ppda->numSector), node->dagHdr->bp);

	/* Now apply all the recovery data. */
	for (i = 0; i < numDataCol - 2; i++)
		rf_applyPDA(raidPtr, node->params[i].p, ppda, qpda,
		    node->dagHdr->bp);

	RF_ETIMER_STOP(timer);
	RF_ETIMER_EVAL(timer);
	if (tracerec)
		tracerec->q_us += RF_ETIMER_VAL_US(timer);

	rf_GenericWakeupFunc(node, 0);
	return (0);
}

RF_CREATE_DAG_FUNC_DECL(rf_PQ_DDLargeWrite)
{
	RF_PANIC();
}


/*
 * Two lost data unit write case.
 *
 * There are really two cases here:
 *
 * (1) The write completely covers the two lost data units.
 *     In that case, a reconstruct write that doesn't write the
 *     failed data units will do the correct thing. So in this case,
 *     the dag looks like
 *
 *	   Full stripe read of surviving data units (not being overwritten)
 *	   Write new data (ignoring failed units)
 *	   Compute P&Q
 *	   Write P&Q
 *
 *
 * (2) The write does not completely cover both failed data units
 *     (but touches at least one of them). Then we need to do the
 *     equivalent of a reconstruct read to recover the missing data
 *     unit from the other stripe.
 *
 *     For any data we are writing that is not in the "shadow"
 *     of the failed units, we need to do a four cycle update.
 *     PANIC on this case. For now.
 *
 */

RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateWriteDAG)
{
	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
	RF_SectorCount_t sectorsPerSU = layoutPtr->sectorsPerStripeUnit;
	int sum;
	int nf = asmap->numDataFailed;

	sum = asmap->failedPDAs[0]->numSector;
	if (nf == 2)
		sum += asmap->failedPDAs[1]->numSector;

	if ((nf == 2) && (sum == (2 * sectorsPerSU))) {
		/* Large write case. */
		rf_PQ_DDLargeWrite(raidPtr, asmap, dag_h, bp, flags, allocList);
		return;
	}
	if ((nf == asmap->numStripeUnitsAccessed) || (sum >= sectorsPerSU)) {
		/* Small write case, no user data not in shadow. */
		rf_PQ_DDSimpleSmallWrite(raidPtr, asmap, dag_h, bp, flags,
		    allocList);
		return;
	}
	RF_PANIC();
}

RF_CREATE_DAG_FUNC_DECL(rf_PQ_DDSimpleSmallWrite)
{
	rf_DoubleDegSmallWrite(raidPtr, asmap, dag_h, bp, flags, allocList,
	    "Rq", "Wq", "PQ Recovery", rf_PQWriteDoubleRecoveryFunc);
}

#endif	/* (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0) */
